Field of the Invention
The invention relates to a hearing aid having an antenna device for receiving and/or transmitting electromagnetic waves with a predetermined wavelength lambda, wherein the antenna device has a frame for holding assemblies of the hearing aid. The invention also relates to a method for producing a hearing aid.
Hearing aids are portable hearing apparatuses that are used for the care of the hard of hearing. In order to meet the numerous individual needs, different structures of hearing aids are provided, such as behind-the-ear hearing aids (BTE), hearing aids with an external receiver (RIC: receiver in the canal) and in-the-ear hearing aids (ITE), e.g. including concha hearing aids or channel hearing aids (ITE, CIC). The hearing aids mentioned by way of example are worn on the external ear or in the auditory canal. Furthermore, bone-conduction hearing aids, implantable hearing aids or vibrotactile hearing aids are also commercially available. In this case, the damaged hearing is stimulated either mechanically or electrically.
In principle, the important components of hearing aids are an input transducer, an amplifier and an output transducer. The input transducer is normally an acousto-electrical transducer, e.g. a microphone, and/or an electromagnetic receiver, e.g. an induction coil. The output transducer is generally an electro-acoustic transducer, e.g. a miniature loudspeaker, or an electromechanical transducer, e.g. a bone-conduction receiver. The amplifier is usually integrated in a signal processing device.
In the past, hearing aids have often been regarded as individual systems that reproduce acoustic signals picked up by microphones in appropriately modified and amplified form. Magnetically inductive radio systems have combined those individual systems into an overall system that permits not only binaural coupling of the hearing aids but also wireless connection to external components, such as mobile appliances, multimedia units or programming appliances. However, that connection works only through an intermediate or relay station that converts the 2.4 GHz far-field connection of the external appliances to the magnetic inductive near-field systems by using Bluetooth. In that case, the relay station must always be in proximity to the hearing aid wearer, because the range of the magnetic system is severely limited in the near field.
For a long time, direct connection in the 2.4 GHz far field was limited by the power consumption and size of such systems. However, modern chip systems now have a power consumption that permits use in hearing aids. The sensitivity of the chip systems still makes great demands on the antenna device, however.
Due to the free-space wavelength lambda of more than 10 cm in this band and the electrically small volume of the hearing aid, a standard antenna structure cannot readily be used. Antennas in hearing aids are therefore individual, nonmodular devices that need to be especially adapted to suit the hearing aid.
U.S. Pat. No. 7,593,538 B2 describes an antenna that forms a single-layer or multi-layer loop antenna by using a flexible PCB and is connected to the mother board of the hearing aid.
U.S. Pat. No. 7,450,078 B2 likewise describes a loop antenna that is produced by a single-layer conductor loop in the hearing aid.
European Patent EP1 851 823 B1, corresponding to U.S. Pat. No. 7,646,356, describes an antenna for a hearing aid in which two antenna elements are disposed in spirally shortened fashion on the hearing aid housing.
European Patent EP1 587 343 B1, corresponding to U.S. Patent Application Publication No. 2005/0244024, discloses a hearing aid with an antenna as a conductive layer in the material of the hearing aid housing.
At the short wavelengths, which are in the region of 10 cm at 2.4 GHz, the influence of the head of the wearer on the antenna characteristics is substantial.